Early detection of epidemic outbreaks impacting public health and/or veterinary medicine needs cost-effective, robust and specific assays. Due to these needs, such assays traditionally have been conducted in centralized laboratories, rather than at the point-of-care.
However, Point-Of-Care Testing promises to bring the test to the test subject, in either the field or the clinic, providing more rapid detection with potential benefit to both the test subject and to public health.
In order to facilitate Point-Of-Care Testing, assays should be run without access to large, fragile or expensive equipment commonly found in centralized laboratories. Such equipment may include centrifuges, vortexers, thermocyclers, microscopes and incubators. Furthermore, external power sources may be unavailable in the field, and specialized technicians may not be available to conduct assays. Indeed, in some circumstances it may be desirable for test subjects to conduct self-testing.
A few companies have successfully designed high specificity Point-Of-Care Testing equipment relevant to the detection of epidemic outbreaks. To achieve high specificity, this equipment typically relies on Polymerase Chain Reaction (PCR), conducted in the field, to confirm the presence of a suspected pathogen or agent. The Bioseeq device from Smiths (Herts, U.K.) is one such hand-held instrument that can accurately detect bacterial and viral agents. Idaho's Razor (Salt Lake City, Utah) and Selex's Nexsense B (Edinburgh, U.K.) are two other commercially available systems.
Although PCR systems provide excellent specificity, they also greatly increase costs as compared to other less specific assay kits, such as an Enzyme-Linked Immunosorbent Assay (ELISA). Furthermore, PCR systems need very clean samples, necessitating large upfront investment in sample preparation platforms that effectively integrate with microfluidic sample handling and readout. As an example of PCR-based Point-Of-Care Testing capital expenditures, the Bioseeq device has a base unit price in excess of $10,000 (the base unit is used in conjunction with consumable sample insert cartridges).
In order to provide high specificity Point-Of-Care Testing equipment without necessitating formidable upfront investment by the end user, radical simplification of the processes used by current PCR-based Point-Of-Care Testing equipment is needed. Specifically, there is a need for affordable, rapid, specific and accurate Point-Of-Care Testing assays that are completely disposable, or that need only nominal upfront investment. In order to accomplish this, complex interactions at the interface of biology, chemistry and material science should be harnessed synergistically (FIG. 1).